1. Field of the Invention
The present invention relates to a frame structure used in a backlight module and, more particularly, to a frame structure for fixing the components of a backlight module for illuminating a liquid crystal panel.
2. Description of Related Art
In recent years, the liquid crystal display device has been commonly applied in the information technologies. In particular, owing to the mature manufacturing technique, the price of the liquid crystal display device has become cheaper, which also further benefits the popularity of the liquid crystal display device.
Generally speaking, displaying method of the liquid crystal display device is passive, which means that there must be a backlight module to illuminate the liquid crystal panel, and thereby the images displayed on the liquid crystal display device can be seen. Therefore, the liquid crystal display device must be mounted with a backlight module. As shown in FIG. 1, the liquid crystal display device is composed of several minute and complex elements. Commonly, a liquid crystal panel 4 as well as the components of a backlight module, e.g. a linear light source 6, a light source fixer 9, a light guide 12, an upper diffusing plate 13, a prism plate 14, a reflective plate 15, and a lower diffusing plate 16, are assembled between an outer frame 5 and a lower frame 2. The outer frame 5 is made of metal and optionally combined with a plastic upper frame 1, and the lower frame 2 is made of metal or plastic. Among those elements, the lower frame 2 is made of metal or plastic. Among those elements, the assembling frames, i.e. the outer frame 5, the upper frame 1, and the lower frame 2 must have good fixing ability and assembling characteristics.
U.S. Pat. No. 5,729,310 disclosed a lighting apparatus, which fixed the upper frame to the lower frame by at least a pair of protrusions produced on one of the upper and lower frames and a recess formed on the other frame to engage with the protrusions. Commonly, the recess for engaging the protrusion has excess space in order to facilitate the engagement. However, the space might lead to a loose engagement between the protrusion and the recess, and make the fixing between the upper and lower frames not firm enough.
Currently, the backlight module utilizes an upper frame A and a lower frame B to receive the components of a backlight module, as shown in FIG. 2. The upper frame A has a plurality of square buckling elements a, which can buckle with the protruding elements b formed at the periphery of the lower frame B for fixing the upper frame A to the lower frame B. Similarly, the upper frame A has to include a gap c for facilitating the buckling between the square buckling elements a—and the protruding elements b, as shown in FIG. 3. As a result, the fixing efficiency is compromised.
Thus, no matter whether the protrusion or the square buckling element is used, it can restrain the relative movement between the upper and lower frames in the upright direction, but it cannot restrain the relative movement between the upper and lower frames in the cross direction effectively. Consequently, the assembling frame of the backlight module currently used cannot provide an effective fixing function.
Therefore, it is desirable to provide an improved frame structure used in a backlight module to mitigate and/or obviate the aforementioned problems.